linux-kernel - Re: [PATCH RESEND v3 05/10] mm/vma: de-duplicate __vma_enter

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAJuCfpEv+aag1s2Aa=moCueyfB38hmSJFJ4ieZwthRdsKZEhWA@mail.gmail.com>
Date: Thu, 22 Jan 2026 11:39:34 -0800
From: Suren Baghdasaryan <surenb@...gle.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, David Hildenbrand <david@...nel.org>, 
	"Liam R . Howlett" <Liam.Howlett@...cle.com>, Vlastimil Babka <vbabka@...e.cz>, 
	Mike Rapoport <rppt@...nel.org>, Michal Hocko <mhocko@...e.com>, Shakeel Butt <shakeel.butt@...ux.dev>, 
	Jann Horn <jannh@...gle.com>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	linux-rt-devel@...ts.linux.dev, Peter Zijlstra <peterz@...radead.org>, 
	Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>, Boqun Feng <boqun.feng@...il.com>, 
	Waiman Long <longman@...hat.com>, Sebastian Andrzej Siewior <bigeasy@...utronix.de>, 
	Clark Williams <clrkwllms@...nel.org>, Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH RESEND v3 05/10] mm/vma: de-duplicate __vma_enter_locked()
 error path

On Thu, Jan 22, 2026 at 5:02 AM Lorenzo Stoakes
<lorenzo.stoakes@...cle.com> wrote:
>
> We're doing precisely the same thing that __vma_exit_locked() does, so
> de-duplicate this code and keep the refcount primitive in one place.
>
> No functional change intended.
>
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

Reviewed-by: Suren Baghdasaryan <surenb@...gle.com>

> ---
>  mm/mmap_lock.c | 21 ++++++++++++---------
>  1 file changed, 12 insertions(+), 9 deletions(-)
>
> diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c
> index 9563bfb051f4..7a0361cff6db 100644
> --- a/mm/mmap_lock.c
> +++ b/mm/mmap_lock.c
> @@ -45,6 +45,14 @@ EXPORT_SYMBOL(__mmap_lock_do_trace_released);
>
>  #ifdef CONFIG_MMU
>  #ifdef CONFIG_PER_VMA_LOCK
> +
> +static inline void __vma_exit_locked(struct vm_area_struct *vma, bool *detached)
> +{
> +       *detached = refcount_sub_and_test(VM_REFCNT_EXCLUDE_READERS_FLAG,
> +                                         &vma->vm_refcnt);
> +       __vma_lockdep_release_exclusive(vma);
> +}
> +
>  /*
>   * __vma_enter_locked() returns 0 immediately if the vma is not
>   * attached, otherwise it waits for any current readers to finish and
> @@ -77,7 +85,10 @@ static inline int __vma_enter_locked(struct vm_area_struct *vma,
>                    refcount_read(&vma->vm_refcnt) == tgt_refcnt,
>                    state);
>         if (err) {
> -               if (refcount_sub_and_test(VM_REFCNT_EXCLUDE_READERS_FLAG, &vma->vm_refcnt)) {
> +               bool detached;
> +
> +               __vma_exit_locked(vma, &detached);
> +               if (detached) {
>                         /*
>                          * The wait failed, but the last reader went away
>                          * as well.  Tell the caller the VMA is detached.
> @@ -85,7 +96,6 @@ static inline int __vma_enter_locked(struct vm_area_struct *vma,
>                         WARN_ON_ONCE(!detaching);
>                         err = 0;
>                 }
> -               __vma_lockdep_release_exclusive(vma);
>                 return err;
>         }
>         __vma_lockdep_stat_mark_acquired(vma);
> @@ -93,13 +103,6 @@ static inline int __vma_enter_locked(struct vm_area_struct *vma,
>         return 1;
>  }
>
> -static inline void __vma_exit_locked(struct vm_area_struct *vma, bool *detached)
> -{
> -       *detached = refcount_sub_and_test(VM_REFCNT_EXCLUDE_READERS_FLAG,
> -                                         &vma->vm_refcnt);
> -       __vma_lockdep_release_exclusive(vma);
> -}
> -
>  int __vma_start_write(struct vm_area_struct *vma, unsigned int mm_lock_seq,
>                 int state)
>  {
> --
> 2.52.0